 /*******************************************************************************
  * Copyright (c) 2000, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.externaltools.internal.model;

  
 import java.util.HashMap ;
 import java.util.Iterator ;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.widgets.Display;

 /**
  * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
  */
 public class ImageDescriptorRegistry {

     private HashMap fRegistry= new HashMap (10);
     private Display fDisplay;
     
     /**
      * Creates a new image descriptor registry for the current or default display,
      * respectively.
      */
     public ImageDescriptorRegistry() {
         this(ExternalToolsPlugin.getStandardDisplay());
     }
     
     /**
      * Creates a new image descriptor registry for the given display. All images
      * managed by this registry will be disposed when the display gets disposed.
      *
      * @param display the display the images managed by this registry are allocated for
      */
     public ImageDescriptorRegistry(Display display) {
         fDisplay= display;
         Assert.isNotNull(fDisplay);
         hookDisplay();
     }
     
     /**
      * Returns the image associated with the given image descriptor.
      *
      * @param descriptor the image descriptor for which the registry manages an image
      * @return the image associated with the image descriptor or <code>null</code>
      * if the image descriptor can't create the requested image.
      */
     public Image get(ImageDescriptor descriptor) {
         if (descriptor == null)
             descriptor= ImageDescriptor.getMissingImageDescriptor();
             
         Image result= (Image)fRegistry.get(descriptor);
         if (result != null)
             return result;
     
         Assert.isTrue(fDisplay == ExternalToolsPlugin.getStandardDisplay(), ExternalToolsModelMessages.ImageDescriptorRegistry_Allocating_image_for_wrong_display_1);
         result= descriptor.createImage();
         if (result != null)
             fRegistry.put(descriptor, result);
         return result;
     }

     /**
      * Disposes all images managed by this registry.
      */
     public void dispose() {
         for (Iterator iter= fRegistry.values().iterator(); iter.hasNext(); ) {
             Image image= (Image)iter.next();
             image.dispose();
         }
         fRegistry.clear();
     }
     
     private void hookDisplay() {
         fDisplay.disposeExec(new Runnable () {
             public void run() {
                 dispose();
             }
         });
     }
 }


